One particularly celebrated perk of breastfeeding is the calorie burn it entails. Since your breasts essentially become milk-producing factories during pregnancy and turn into a 24-hour bar after you give birth, they are working overtime. Each fluid ounce of breast milk contains just over 20 calories, and exclusively breastfed babies consume an average of 25 ounces per day in the first six months of life. Sound confusing? I'll do the math for you: you're looking at an average of about 500 additional calories burned per day. That figure is higher if you've got a voracious little one, or perhaps lower if his or her appetite or your production is more modest. To reflect this wide variation in milk production among women, the American Pregnancy Association estimates that new mothers burn an extra 425 to 700 calories per day in the process of breastfeeding alone.

But there's more! Aside from the massive calorie burn, breastfeeding may also specifically tighten your midsection, thanks to oxytocin, a hormone released during lactation. Oxytocin causes uterine contractions, which, during labor, are enormously helpful (and enormously painful). But after delivery, the low-grade oxytocin release that occurs with lactation can help shrink your uterus back down to its prepregnancy size. And emerging evidence also indicates that women who breastfeed appear to have lower rates of cardiovascular disease, gynecologic cancers, and even diabetes compared to moms who didn't breastfeed. Long story short: bar's open!